truffle-config.js

const HDWalletProvider = require("truffle-hdwallet-provider");

require('dotenv').config();  // Store environment-specific variable from '.env' to process.env

module.exports = {
  /**
   * Networks define how you connect to your ethereum client and let you set the
   * defaults web3 uses to send transactions. If you don't specify one truffle
   * will spin up a development blockchain for you on port 9545 when you
   * run `develop` or `test`. You can ask a truffle command to use a specific
   * network from the command line, e.g
   *
   * $ truffle test --network <network-name>
   */

  networks: {
    matic: {
      provider: () => new HDWalletProvider(process.env.PK, `https://testnetv3.matic.network`),
      network_id: 15001,
      gasPrice: '1000000000',
      confirmations: 5,
      timeoutBlocks: 200,
      skipDryRun: true
    }
  }
}